A doubtful structure of Cd-I2 (mp-582042)

Materials Project
1

Hi,

I encountered a doubtful compound structure in this database: Cadmium Iodide (mp-582042). Among the 124 Cadmium Iodide structures, this one has the lowest energy above hull (most stable).

In the material project database, the crystal structure is “None” and the symmetry group is “[]”. According to wikipedia (https://en.wikipedia.org/wiki/Cadmium_iodide), however, the compound has the crystal type “trigonal” and the space group “P3m1”.

Does anyone know the reasons for the discrepancies? How can I get the original references or contact the authors?

Thank you in advance,

Eric

2

Hi Eric,

I guess you were talking about https://materialsproject.org/materials/mp-567259/, who has a trigonal primitive cell and space group of P3m1.

The symmetry data of mp-582042 is definitely wrong. Thanks for reporting the issue. This is due to an issue of an old software, which cannot recognize the elongated cell. We are in a working progress now to rebuild the database, and will update the result with the correct value soon. Please stay tuned.

Best,

Miao

3

Hi Eric,

Just so you know that the compound mp-582042, has the correct symmetry data now.

Please check it out, https://materialsproject.org/materials/mp-582042/

Miao

1 Like
4

Hi Miao,

Thank you for your reply. Very helpful!

Eric

5

Hi Miao,

I found most of Cd-I structures have been updated from “None” to a definite space group.

Nevertheless, there are still 8 structures having “None”: mp-571667, mp-571516, mp-680163, mp-669340, mp-680172, mp-680095, mp-680196, mp-703595.

I wonder if it is because the update is still going on, or these structures are unidentifiable, or they are considered amorphous. Thanks!

6

Hi Eric,

They are not amorphous. Any compound we calculated has a well-defined crystal structure, hence should have a space group. Some of them are missing due to a bug of a previous version of pymatgen. We are running a data rebuild to address the all possible issues caused by the bug and it will take some time to finish updating all of them. They will be assigned a space group in the near future.

Thank you again for using our website and reporting the issue.

Miao

7

Got it. Thanks!

Eric